How Soon Can an Ultrasound Show a Baby’s Heartbeat?

Amidst the excitement around having a baby comes the nerve-wracking first few weeks as soon-to-be parents wait to learn if their pregnancy is progressing as expected. One of the first milestones during pregnancy is hearing the baby’s heartbeat. But how soon can an ultrasound show a baby’s heartbeat? The answer to this question depends on a few factors, such as the stage of pregnancy, the type of ultrasound used, the pregnancy being dated correctly, and the skill of the person performing the ultrasound.

How Pregnancies are Dated

There is more than one way to calculate how many weeks pregnant a woman is. The date of fertilisation may be counted as the first day of pregnancy, or the date may be calculated based on the last menstrual cycle. Typically, the date of fertilisation is unknown, so measuring from the last period is more common. When dating a pregnancy based on the missed menstrual cycle, the two weeks before conception is included. The time frame, including the two weeks before the missed period, is known as the gestational age of the embryo or fetus.

How an Embryo Develops

Medically speaking, only eight weeks after fertilisation, or by the end of the tenth week of pregnancy, is the embryo deemed a fetus. By this time, all the major organ systems have begun to form. While the cardiovascular system is the first to develop, the heart has only developed its primary structures by about nine weeks of pregnancy. Some ultrasound devices will reveal cardiac activity by the sixth week; however, this is not a heartbeat but rather electrically induced flickering in the area where the heart will develop.

Detecting the Heartbeat

After six weeks of pregnancy, electrical activity can be detected in the embryo. This early on, a transvaginal ultrasound needs to be performed to get closer to the developing embryo. The tiny flicker of cardiac activity can only be seen at this stage, not heard. Still, seeing this activity depends on the quality of the ultrasound machine, the weight of the patient, and the position of the embryo and uterus. If the pregnancy has not been dated correctly, this may also affect whether the activity can be detected.

Parents may assume they are hearing the heartbeat during the ten to fourteen-week scan when conducted using a handheld Doppler fetal monitor or acoustic Doppler. This pulsing noise, however, is the sound the machine produces rather than the sound of blood circulating in the fetus. The actual heartbeat is only audible by about 20 to 22 weeks using a standard stethoscope. Alternatively, the fetus can be seen, and its heartbeat heard using a Doppler ultrasound, which is different from the handheld Doppler fetal monitor or acoustic Doppler.

Based on these factors, some women may hear their baby’s heartbeat sooner than others. If you are concerned about not hearing your baby’s heartbeat as early as you would like, speak to your doctor, sonographer, or midwife. They will be able to perform an ultrasound and let you know if everything is progressing as it should.

OMNI Ultrasound & Gynaecological Care

Condous performs Advanced Endosurgery procedures for women needing intervention for pelvic masses, adnexal pathology, severe endometriosis or hysterectomy. He also runs ‘Hands on’ Live Sheep Laparoscopic Workshops for gynaecologists at Camden Veterinarian School.
Having completed an undergraduate degree with the University of Adelaide, he left Australia in 1993 and moved to London where he completed his training in Obstetrics and Gynaecology. From 2001 to 2003 Condous worked as a Senior Research Fellow at St George’s Hospital, London. At St George’s he set up the Acute Gynaecology Unit, the first in the United Kingdom. It was also during this time that he developed an interest in Early Pregnancy and especially the management of pregnancies of unknown location (PULs). Condous has developed many mathematical models for the prediction of outcome of PULs which have been featured in numerous peer review journals. In 2005, he returned to Australia where he completed his Laparoscopic Fellowship at the Centre for Advanced Reproductive Endosurgery, Royal North Shore, Sydney.

Condous was appointed as a Consultant Gynaecologist and Senior Lecturer at Nepean Hospital in 2006 and soon was made Associate Professor. In 2010, he was made Departmental Head of Obstetrics and Gynaecology at Nepean Hospital. He obtained the MRCOG in 1999 and was made FRANZCOG in 2005. In 2009, he was awarded his Doctorate in Medicine (MD), University of London, for his thesis entitled: “The management of pregnancies of unknown location and the development of new mathematical models to predict outcome”.

Condous has edited three books including the “Handbook of Early Pregnancy Care”, published over 100 papers in international journals and is internationally renowned for his work in Early Pregnancy. He is the Associate Editor for Gynaecologic Obstetric Investigation, which is a European based journal, as well as the Australasian Journal of Ultrasound in Medicine (AJUM). He is on the organising committee and is an invited speaker at the International Society of Ultrasound in Obstetrics and Gynaecology (ISUOG) Scientific meeting in Sydney 2013. His current research interests relate to the management of ectopic pregnancy, 1st trimester growth, PULs and miscarriage and the use of transvaginal ultrasound (in particular sonovaginography, to predict posterior compartment deep infiltrating rectovaginal endometriosis).Condous is also actively involved with post-graduate education including the annual running of the Early Pregnancy and Gynaecological Ultrasound Interactive Courses for Sonologists, Radiologists, Sonographers and Gynaecologists in Australia.